Background Home range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before. Methodology/Principal Findings The first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km2 in a non-fragmented forest and 600 km2 in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another. Conclusions/Significance Home range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans.

et al. (2012) Home Range and Ranging Behaviour of Bornean Elephant (Elephas maximus borneensis)
Females. PLoS ONE 7(2): e31400. doi:10.1371/journal.pone.0031400
Home Range and Ranging Behaviour of Bornean Elephant (Elephas maximus borneensis ) Females
Raymond Alfred 0
Abd Hamid Ahmad 0
Junaidi Payne 0
Christy Williams 0
Laurentius Nayan Ambu 0
Phua Mui How 0
Benoit Goossens 0
Matt Hayward, Australian Wildlife Conservancy, Australia
0 1 Borneo Species Programme, World Wildlife Fund-Malaysia , Kota Kinabalu, Sabah, Malaysia, 2 Borneo Conservation Trust , Sabah Wildlife Department , Kota Kinabalu, Sabah , Malaysia , 3 Institute for Tropical Biology and Conservation , Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia, 4 Borneo Rhino Alliance (BORA) , Institute for Tropical Biology and Conservation , Universiti Malaysia Sabah, Kota Kinabalu, Sabah , Malaysia , 5 World Wildlife Fund Asian Rhinoceros and Elephant Action Strategy, World Wildlife Fund-International, Gland, Switzerland, 6 Sabah Wildlife Department , Kota Kinabalu, Sabah , Malaysia , 7 School of International Forestry, Universiti Malaysia Sabah , Kota Kinabalu, Sabah , Malaysia , 8 Danau Girang Field Centre, Sabah Wildlife Department , Kota Kinabalu, Sabah , Malaysia , 9 Organisms and Environment Division, School of Biosciences, Cardiff University , Cardiff, United ingdom
Background: Home range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before. Methodology/Principal Findings: The first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km2 in a non-fragmented forest and 600 km2 in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another. Conclusions/Significance: Home range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans.
-
Funding: This specific study was supported by grants from World Wildlife Fund-United States, United States. Fish and Wildlife Service Asian Elephant
Conservation Fund, World Wildlife Fund -Netherlands and World Wildlife Fund -Germany. The funders had no role in study design, data collection and analysis,
decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
The Asian elephant inhabits many types of habitat throughout
its range, including closed canopy tropical rainforest in Peninsular
Malaysia, Sumatra and Borneo. These three land masses were
part of Sundaland, an extension of the continental shelf of
SouthEast Asia, most of which now lies under the South China Sea [1].
In recent decades, commercial logging of the forests was followed
by large-scale conversion of logged forests to agriculture and by
the establishment of settlements in these three parts of Sundaland.
As a result, the available elephant habitat was reduced, forcing a
large percentage of these animals to migrate to other areas with a
change in their feeding behavior since the natural habitat was
affected and the food supply was depleted [2].
Home range is defined as the extent and location of the area
covered annually by a wild animal in its natural habitat [3].
Studies of African and Indian elephants in landscapes of largely
open habitats have indicated that the size of their home range is
determined by a combination of factors including ongoing human
disturbance [4], food supply, seasonal changes, availability of
water sources [5] and the existence of man made barriers such as
canals and also habitat loss [6]. For the Asian elephant, there is
considerable evidence that indicates home ranges are influenced
by the availability of suitable habitat [2]. Sukumar [2] also
emphasized that the more diverse a habitat is for an Asian
elephant, the smaller the required home range as elephants would
be able to meet their varied needs within a relatively small area.
To our knowledge, the home range size for the Bornean elephant
has not been reported, probably due to the difficulty of tracking
individuals in the forest. The only available information on the
Asian elephants home range in Sundaland rainforests was
reported by Olivier [7] to be 59 to 167 km2 in Peninsular
Malaysia.
As the home ranges of introduced feral animals may be
significantly different to animals that had evolved in that habitat, it
is important to emphasise that the origin of the Bornean elephant
is still controversial, despite the publication of a molecular study
indicating the genetic distinctiveness of the Bornean elephant and
its derivation from Sundaic stock [8]. The authors also claimed
independent evolution of the Bornean elephant for some 300,000
years since a postulated Pleistocene colonization and recognized it
as native to Borneo and as a separate evolutionary significant unit.
However, it seems unlikely that a taxon assumed to be present in
Borneo for more than 300,000 years, and therefore subject to
evolutionary pressures, presents only one maternal lineage as
compared with orang-utans or proboscis monkeys which harbour
several maternal lineages and are also present on the island since
the Pleistocene [910]. More strikingly, there have been no
authenticated or confirmed finds of Asian elephant in any
controlled excavation, including the Niah cave (Sarawak) or the
Madai cave (Sabah, within the species present range) although
other large ungulates (Rhinocerus sondaicus and Dicerorhinus
sumatrensis, Tapirus indicus) were excavated. Cranbrook et al. [11] took
into account such facts and postulated a different theory: elephants
from Java were sent to Sulu at the end of the 14th century as a gift
between Sultans, proliferated on the island and subsequently
provided the founder members of the existing population of
northeast Borneo. However, it remains unclear when and how
many founders were translocated to Borneo by the Sultan of Sulu.
Elephants were reported to be present on Sulu until the beginning
of the 19th century but they were finally exterminated by 1850
[11]. Therefore, Borneo may have been the refuge of the Javan
elephant and Elephas maximus borneensis the descendant of E. m.
sondaicus. This being the case, these elephants have only inhabited
Sabah for between 500 to 600 years.
The successful application of satellite tracking systems to follow
large wildlife species in order to determine the size of their home
range and their movement patterns in different habitats has been
possible since the early 1980s [1213]. Particularly for elephants,
it has been used on African savannah elephants (Loxodonta africana
africana) in several countries such as Namibia [1416], Botswana
[17], Mozambique [18], Cameroon [19], Zimbabwe [20], Kenya
[2122] and Tanzania [23], and on African forest elephants (L. a.
cyclotis) in Central African Republic and Congo [2425]. Most of
these studies looked at home range size, habitat use and
preferences, migration and activity patterns, and seasonal
movements. For example, de Beer & van Aarde [16], using
satellite GPS collars, discovered that landscape heterogeneity and
water distribution determined elephant home range location and
size, leading to management measures for the elephants in
conservation areas. In Asia, satellite tracking devices have only
been used in India to determine movement patterns and habitat
use of one individual male elephant [26] and in Peninsular
Malaysia to track the movements of two translocated individuals, a
female and a male [27]. However, scientists have also used VHF
telemetry to study the ranging patterns of 10 elephants in southern
Sri Lanka [28]. Table 1 shows the estimated home ranges of the
Asian elephant in several locations in Asia. Due to some variation
in the methodology (especially to gather the location of the
elephants in the forest) and the degree of completeness of the
gathered data, the estimated home ranges for the Asian elephant
were about 100 km2 to 300 km2, this should be regarded as a
minimum home range in a non-fragmented forest landscape.
This paper presents data on the free ranging Asian elephant of
Borneo in their natural habitat using satellite GPS telemetry
(satellite GPS collars). It also presents data on their movement
patterns obtained from GPS data locations in conjunction with
field observations of the known individuals. In addition, we
estimated (i) the home ranges for the Bornean elephant in
nonfragmented and fragmented forests, and (ii) the minimum period
of tracking needed to determine the home range. We finally
ascertained the typical patterns of elephant movement over time
and determined how fragmented forest and habitat conditions
affect the movement and how it may contribute to
humanelephant conflict.
Capturing and Tracking Elephants
Five female elephants (two large sub-adults and three adults)
were captured and collared between 10 June and 17 July 2005.
Table 2 identifies the location and details of capture of each
elephant and the name given to the herds. Locations of the
captures are shown in Figure 1. Only two of the elephant herds
(Nancy and Bod Tai) were tracked for over a full year in Ulu
Segama-Malua Forest Reserves and Lower Kinabatangan Wildlife
Sanctuary. Table 3 provides the details on period and tracking
performances using satellite GPS collars for each collared
elephant. The performance of the satellite GPS collars used to
track the elephants for one year ranged from 33.846.2%
reliability. The elephants home range derived from this study
Table 1. Estimated home ranging for Asian elephant based on previous studies in Asia and using Minimum Convex Polygon
(MCP).
Size of home range
105 km2 to 115 km2
170 km2 to 320 km2
Visual Observation and radio tracking
A group of adults in Peninsular Malaysia
Visual Observation and radio tracking
Sub-unit that comprises young elephants in
Peninsular Malaysia
Visual Observation and Foot tracking
In Peninsular Malaysia
Radio and GPS tracking
Radio and GPS tracking
In primary forest in Peninsular Malaysia
In secondary forest Peninsular Malaysia
Existing forest type(s)
Successful collarings (date)
7 July 2005 17 July 2005
Name given to
elephants herd
Large immature female
DF for Dipterocarp Forest, HF for Heath Forest, UF for Ultramafic Forest, FSF for Freshwater Swamp Forest, MF for Mangrove Forest.
doi:10.1371/journal.pone.0031400.t002
takes into consideration the performance of the satellite GPS
collars. The home range calculated in this study should be
considered as a minimum home range, since the availability and
predictability of food resources have always been strongly
implicated as having the most important effect on ranging.
a) Home Range. The home range patterns computed using MCP and HM methods are shown on topographical maps (Figures 2 and 3), while the numerical results are summarized in Table 4.
Number of GPS
location obtained
No of days with GPS
location obtained
% of tracking
(Daily tracking)
7 July 2005 17 July 2005 Tracking record dates
13 June4 July 2005
7 July 20057 July 2006 366 days 17 July4 November 2005 110 days 21 days
As Rozelis was only tracked for a short period of time, we did not
use the data in the analysis. Tailiwas and Nancy herds shared the
same forest area and had a home range of 330.41 km2 and
244.97 km2 respectively (HM method, with 95% isopleths). Although
Tailiwas was only monitored for 216 days, the home range of her
herd was bigger than Nancys herd. The home range for Penelopes
herd covered about 414.8 km2 over a period of 3.5 months.
The home range for Bod Tais herd calculated by the MCP was
778.62 km2. This figure is misleading because it incorporates
extensive areas of oil palm plantations and permanent swamp
forest, where elephants may not be able to access because the
plantations are secured or protected by electrical fences, and they
are known to rarely if ever enter swamp forest. In comparison, the
HM method (95% isopleths) estimated the home range to be
593.02 km2. This is considered to be a much more accurate and
reliable home range area. Although Bod Tais herd lives in
marginal and fragmented habitat (isolated from the main elephant
habitat of central Sabah, elephants have to travel periodically
through plantations and villages, in a generally swampy and flood
prone region), parts of the habitat provide fast-growing grasses and
Tracking Period (days)
Home Range (km2) using MCP
Core Area 1 (km2) using HM with 65% isopleths
Core Area 2 (km2) using HM with 75% isopleths
Core Area 3 (km2) using HM with 85% isopleths
Average Monthly Ranging (MCP)
SD for Monthly Ranging (MCP)
SE for Monthly Ranging (MCP)
Average Monthly Ranging (HM)
SD for Monthly Ranging (HM)
SE for Monthly Ranging (HM)
other nutritious plants on fertile soils of the Lower Kinabatangan
that are favoured by the elephants.
The amount of suitable habitat for elephants in Lower
Kinabatangan may now be too small and too fragmented to support
an elephant population in the long term. Although the elephant
population in this area appears to be increasing, based on the
frequency of infant elephants seen in all herds, it will not be able to
expand, as they are isolated by roads, plantations and human
settlements.
b) Monthly Ranging. The monthly ranging of the monitored
elephants was analyzed based on the location data gathered from
the satellite GPS collar for each month. The monthly ranging that
is generated using MCP and HM methods is presented in Table 4.
The monthly ranging of the elephants in the non-fragmented forest,
based on three different individuals was between 50 to 60 km2 (using
MCP method) and 103 to 192 km2 (using HM method, 95% isopleths).
The monthly ranging of the elephants in the fragmented forest, based
on one individual was 120.86642.60 (using MCP method) and
227.566123.05 (using HM method, 95% isopleths). It would seem that
the monthly ranging of the elephant in the non-fragmented forest is
smaller compared to the one in the fragmented forest.
The highest monthly ranging for the elephant in the fragmented
forest was recorded during March 2006, when Bod Tais herd
moved along a narrow riparian strip in Lower Kinabatangan, and
utilized patches of fragmented forest. Figures 4 and 5 show the
monthly ranging for Bod Tais herd and Nancys herd for one year
(generated using the Harmonic Mean with 95% isopleths).
Using the Harmonic Mean with 95% isopleths, the monthly
ranging for Nancys herd covered 110.27610.70, which was
similar to Tailiwass herd range of 103.77627.25. However, the
monthly ranging for Penelopes herd was twice as big, estimated at
191.25668.32.
Elephant Movement Patterns
The satellite tracking data provided an opportunity to analyze
the rates at which the five collared individuals moved within their
home ranges in different habitat types. The speed of the elephant
movements was computed by generating the average distance
taken by the monitored elephant in one full day, based on the
available GPS location data and the time between successive
locations (Table 5).
Rozeliss movement rate (based on distance per day) during the
first day was observed to be high at 2.86 km presumably due to
the stress of being captured and collared. Field observations of
Rozelis showed that she was isolated from her herd for the first two
days after collaring. From the third day her movement rate varied
from 0.75 to 1.20 km per day. She joined her herd after one week.
Figure 4. Monthly ranging for BodTais herd in fragmented forest (using Harmonic Mean 95% isopleths).
doi:10.1371/journal.pone.0031400.g004
Figure 5. Monthly ranging for Nancys herd in fragmented forest (using Harmonic Mean 95% isopleths).
doi:10.1371/journal.pone.0031400.g005
Tailiwass movement rate on the first day was about 1.56 km.
The longest distance moved (4.29 km) was detected on 15th
September 2005, when the herd moved into Devata village and
was chased away by villagers. During the 12-month study period
the herd entered the village at least twice. The distance moved per
day for this herd ranged from 0.75 to 2.90 km.
Nancys movement rate during the first day after collaring was
about 0.52 km. In general, the movement rate for this elephant
herd was similar to Tailiwas herd, except that Nancys herd
entered the village area only once. The distance moved per day for
this herd ranged from 0.30 to 3.80 km.
Bod Tais herd moved at least 6.7 km in the first day after
collaring. The distance moved per day for this herd ranged from
0.30 to 9.50 km. Bod Tais herd moved more than 9.52 km one
day after the herd was chased away from Sukau village. Movement
of this elephant herd was high when they moved along a narrow
corridor of natural vegetation along the banks of the
Kinabatangan River bordering an oil palm plantation and through
Number of days with
consecutive GPS locations
Mean rate of
movement (Km/day)
swamp forest, where elephants food is limited and where travel for
a large mammal was difficult.
The movement rate of Penelope and her herd was higher when
they were crossing from upland forest to lowland forest using an
abandoned logging road in Gunung Rara Forest Reserve,
traveling at least 2.90 km per day. The distance moved per day
for this herd ranged from 0.75 to 2.90 km. This higher movement
rate is probably due to the herd needing to access water sources
which are only available in a lowland forest. The elephants will use
abandoned logging roads as their migratory routes especially in the
upland or higher terrain, due to the higher abundance of food
sources (i.e. grass), which contain higher water volume.
The monitored elephants exhibited a mixture of movement
rates in different types of forest. For example, they moved more
frequently and over larger distances whenever they were utilizing
fragmented forests. In the fragmented forests of the Lower
Kinabatangan, changes in monthly movement patterns were
expected as human settlements occur and barriers such as electric
fences have been erected, altering movement patterns.
Harassment by humans also influenced the direction and speed of
movement. In non-fragmented forests elephants were less erratic
in their observed movement pattern.
Figure 6 shows the daily movement pattern for the five
elephants. In non-fragmented dipterocarp forest the average
movement rate for the elephants was 1.3060.10 km per day
and the maximum distance moved in a day was 2 km. In contrast,
in highly fragmented forest the rate of travel was 1.8160.18 km
(40% higher) per day and maximum distance moved in a day was
4 km.
Habitat Utilization
Figure 7 shows the percentage of the forest habitat type utilised
by each herd within its home range (determined by MCP) and
Figure 8 shows the percentage of areas with different altitude
utilised. The elephant herds spent the majority of their time below
300 m of altitude.
Figure 8. Estimated percentage of areas with different altitude classes, utilised by the monitored elephants.
doi:10.1371/journal.pone.0031400.g008
Estimation of the Home Ranges for Bornean Elephants in
Fragmented and Non-fragmented Habitats
Based on the field observations, it is considered unlikely that the
elephants spent much or any time in ultrafamic forests and in palm
oil plantations. The former presents limited water sources and
elephant food plants in addition to the toxic heavy metals present
in leaves (derived from the metal rich ultrafamic soils), while in the
latter there are no plants suitable for foraging. The elephant herds
spent the majority (ranging between 65%95%) of their time in
dipterocarp forest, except for Bod Tais herd in the Lower
Kinabatangan where most of the habitat utilised by the elephants
was freshwater swamp forest. The fact that most of the previous
lower land dipterocarp forests that were located within the
Kinabatangan habitat landscape were already converted into oil
palm plantations might explain the results for this region. In
rainforest areas, the home range size of family groups was
suggested to be larger in primary forest (up to 167 km2), where
food plants are less abundant, than in secondary forest (up to
59 km2) [7]. Contrarily, the current study shows that the herds
home range size in secondary forest was greater (248 km2 to
317 km2) than the one previously reported [7]. The difference
between the current results and those from preceding researchers
[7] may be due to several factors [29], particularly by the
availability of suitable forest habitat and permanent water.
Different forest types and conditions provide different diversity
and density of food resources, including the availability of
permanent water, all of which influence the home range size.
Tailiwas and Nancys herds were tracked in the Ulu Segama
Forest Reserve which is below 300 meters above sea level (asl) and
has been largely logged. Currently the area is composed of
degraded dipterocarp forest with sparse tree cover, and of
secondary forest growing on soils derived from sedimentary rocks.
Penelopes herd was also found to utilize the same forest type and
condition; this could be due to habitat disturbance from logging
activities being carried out in Gunung Rara Forest Reserve during
the study period.
Based on the estimated home range, the data from the current
study shows that the home range for the collared elephants in
fragmented forest was double that of collared individuals in the
non-fragmented forest habitat. This could reflect the elephants
difficulty to find their daily resource requirements in an
environment that has been greatly altered. The other factors
influencing the home range size are likely to be the conflict
between elephants and humans (settlements and agricultural
activities) and the construction of barriers (channels and fences).
For instance, elephants were recorded to move a longer distance
after being chased by humans; it is likely that their usual
movements were altered to avoid certain areas or their home
range has been altered by human activity. This situation was
experienced and recorded by the tracking team on the ground
during the field observations of Nancys and Tailiwas herds, on a
day the herds were chased by the villagers in Sepagaya village
(located at the south-east of Ulu Segama-Malua Forest Reserves).
The same pattern of movement was also recorded by the tracking
team on the ground during the field observations of Bod Tais herd
when they reached Batu Putih village in Lower Kinabatangan
region.
Estimation of the Minimum Period of Tracking Needed to
Determine the Home Range
The current results showed that collared elephants living in
logged dipterocarp forests completed their annual home range
(maximum home range) within a period of less than six months.
The home range for Tailiwas in the first four months
(316.20 km2) was very similar to Nancys, after 12 months of
movement (291.54 km2). No disturbances, such as logging
activities, were recorded during the study in Nancys home range.
Based on his study in Peninsular Malaysia, Olivier [7] also
suggested that, due to environmental constancy, tracking for six
months would provide a minimum home range for a herd of
elephants. This would be more accurate than if the elephants were
only tracked through a season, although home range size would
undoubtedly continue to increase with a longer monitoring period.
Typical Patterns of Elephant Movement in (i)
Nonfragmented Forest; (ii) Fragmented Forest; and (iii) in
Different Levels of Disturbance
Elephants were shown to live mostly in lower forest with altitude
ranging from 150300 metres. It is likely that low altitude forests
are favoured for a number of reasons not the least of which would
be proximity to permanent water sources (elephants require
between 100225 litres of water a day; [2] and [5]), and ease of
movement. In addition, the constant climatic conditions
throughout the year and throughout the study area are unlikely to have a
great seasonal effect on food availability. It also can be assumed
that the relative availability of food remains constant in each forest
area provided the type and quality of the forest is the same. A
higher availability of elephant food in non-disturbed forest should
be manifested in a higher standing of food (density and diversity)
than in disturbed forest (i.e. logging is in progress). There should
also be an increased predictability of food sources, with food either
being less patchily distributed or be in higher concentration, or
both, than in disturbed forest.
The differences in behavioral ecology due to the difference in
forest condition (i.e. fragmented and non-fragmented forest) is
particularly clear for the elephants herds when there are
statistically significant differences between mobility indices
(movement rate) (see Table 5). It is reasonable to assume that elephant
food in the fragmented forest will be depleted more rapidly, to a
point where movement is necessary, and that elephant herds
would need to move further until feeding could be resumed,
especially when compared to non-fragmented forest. Assuming
that equal size herds feed at approximately the same rate and
respond to the same level of depletion in food resources, then it is
also reasonable to assume that herds of comparable size would be
more mobile in fragmented forest than in non-fragmented forest.
This is supported by the collared elephant data that showed there
was greater movement per day by animals in the fragmented forest
compared with those in the continuous forest.
This study also indicates that habitat disturbance had the
greatest effect on the elephants movement. In Gunung Rara
Forest Reserve, logging activities were carried out during the
tracking period and elephants moved greater distances than in
forests that were not being logged. It is likely that food plant
sources would have been depleted and that the elephants would
have been affected by the presence of humans and noise from the
logging activities [7].
Materials and Methods
Tracking the Elephant Herds
Global Positioning Systems (GPS) mounted inside a tracking
collar and combined with a satellite communication transmitter
provide invaluable information on elephant location and
movement. This technology allows locations to be transmitted to the
satellite, and compiled in the computer anytime of the day without
the need for difficult and expensive fieldwork.
The satellite GPS collars were supplied by Africa Wildlife
Tracking, Inc, Pretoria, South Africa. They consisted of a GPS
device, an internal aerial, a transmitter, and a battery. A
counterweight on the collar ensured that the functioning parts of
the unit stayed on top of the elephants neck to allow a clear path
of signal reception from the satellites. The entire collar weighed
between 1315 kg, a minimal weight to be carried by a three-ton
(3,000 kg) elephant [30].
Each tracking device reads its own position via GPS satellites.
This information is sent either to one or four communication
satellites, or to a cellular network. The information is then
transmitted to the globaltrack server (http://www.globaltrack.
com) where it is processed and can be downloaded by the user. A
GPS can be used to determine the exact geographic location with
an accuracy that is much higher than can be achieved with a map
and compass. The accuracy of positions determined with a GPS
ranged from 61 m to 615 m.
The duty cycle of the units was set to download three GPS fixes
per 24-hour period, one every eight hours (0600, 1400 and 2200).
Each satellite GPS collar contained a conventional Very High
Frequency (VHF) transmitter that was used to track the elephants
on the ground. The radio frequencies were ranging from 140 to
150 Hertz.
During the satellite tracking period, elephants were also tracked
on foot. Ground truthing of elephant locations were undertaken in
all habitat types. In Kinabatangan, where the transmission of the
GPS signal from the collar was about 366 days, approximately
77% of the GPS locations received (169 days with GPS location)
were verified on the ground. Other location data could not be
verified due to the difficulty of accessing the areas (e.g. swampy
area).
Informal interviews with the oil palm workers were conducted
to determine if the elephants were entering the plantations. It was
revealed that the elephant herds entered the oil palm plantations
occasionally (at least once or twice a year), and stayed in the forest
adjacent to the oil palm plantation for a 12 week period.
Capturing and Collaring Elephants
All animal work has been conducted according to Malaysian
and international guidelines. During a six-week period from June
to July 2005, two large immature and three adult female elephants
were tracked, captured and collared with the satellite tracking
devices in five separate areas in Sabah. Locations of the captures
are shown in Figure 1, and the type of habitat in each capture
location is described in Tables 6 and 7. The elephant herds were
tracked in the early morning (between 0400 to 0630) on foot until
the herds of adult females were found. The ranger armed with a
tranquilizer gun, darted one of the adult female elephants and
then tracked the darted elephant until it was sedated.
Mature female elephants, of a healthy appearance and more
than seven feet in height (over about 30 years of age), were selected
for two reasons: firstly, the study aimed to focus on herds with
young, which are led by a mature female, and secondly, to reduce
potential stress that may have been caused by the weight of collars.
Industrial timber plantation and heavily logged dipterocarp forest combined with one patch of undisturbed dipterocarp forest.
Regenerating logged dipterocarp forest with patches of primary dipterocarp and ultramafic forest
Regenerating logged dipterocarp forest with patches of primary dipterocarp and ultramafic forest
Degraded dryland and freshwater swamp forests, scrub, riverside forest and mangrove, oil palm plantation, villages
Logged dipterocarp and heath forest and primary upland dipterocarp forest (Logging activities were active in this area
during the tracking period)
Name of elephant herd
Ultramafic Forest (UF)
Dipterocarp Forest (DF)
Freshwater Swamp Forest (FSF)
Mangrove Forest (MF)
Peat Swamp Forest (PSF)
Palm Oil Plantation (POP)
The tree canopy averages between 5 and 30 meters tall, but is fairly homogeneous in a particular area. There are few big
lianas, but many slender ones. Trees of the family Myrtaceae usually predominate.
UF varies greatly in structure and species composition, but is usually dominated by species rare or absent from other nearby
forests. On hill slopes, UF tends to have a very even rather low canopy in comparison with DF. The only common factor in all
UF is that it develops on soils derived from ultramafic rock.
The original DF is tall forest which is characterized by the presence of a fairly high biomass density of large trees of the family
Dipterocarpaceae, and often Leguminosae and Lauraceae. The original DF has been very heavily disturbed and nearly all of
plants in DF are secondary growth of different species composition from that in the original forest.
Plant species composition in FSF varies greatly, and may be locally diverse, or dominated by one species. The tree canopy is
generally rather open, but with extensive patches of low scrub in the most poorly-drained areas.
Mangrove is characterized by a relatively few species of trees growing in coastal areas inundated with seawater. Nipah is a
palm, which forms pure species stands where salt and fresh water mix.
The structure of PSF varies greatly, ranging from low, stunted vegetation to forest resembling DF. Floral composition is
equally variable. The habitat is characterized by a layer of peat (slightly decomposed plant material), 0.5 to over 20 m deep
developed on marine alluvium.
POPs are planted on a large scale with species of palm tree, for the purpose of producing oil palm. Most of the DF has been
replaced by POP in Sabah especially in the south-eastern part.
The sedative used was Iliul Xyllazil-100, it took effect within
30 minutes after the first dart was fired successfully, and the effect
lasted for 3040 minutes. Once sedated, the elephant was kept in a
standing position by using small poles pointed at the back of the
elephants ears and the collar with the tracking device was
attached around the elephants neck. To minimize unnecessary
time sedated, an antidote (Reverzine) was administered as soon as
collaring was completed, normally taking less than a minute to
take effect. In some cases, the rest of the herd stayed nearby
throughout the collaring, while in other cases, they fled. The
collared elephant returned to its herd either immediately or within
a few days.
The success of immobilizing and collaring these elephants
depended on finding elephant herds with the right characteristics
(e.g. sex, age and health requirements) within the time period for
fieldwork and the ability of the ground staff to track the herd in the
forest. Seven different areas were identified to conduct the
collaring of wild elephants, but only in five areas were elephants
successfully collared. Of those five areas, four areas were located
within the large block of predominantly logged but
nonfragmented forest cover in central Sabah, and one area was
located in a fragmented floodplain landscape (see Figure 1).
Data Compilation and Analysis
The data obtained from the satellite tracking was compiled by
using the web-based application developed by Global Track
(www.globaltrack.com). The GPS collar device was programmed
to transmit the GPS locations every 8 hours (0200, 1000, and
1800). During the daytime, elephants were sighted resting in the
forest between 0900 to 1500, and during this time very few
signals were transmitted due to forest canopy cover. GPS
locations were only transmitted when the elephants were in the
open areas, such as in riverine (this was especially during the
evening) or logged forest. In order to analyze habitat utilisation,
only home range data that was collected for a period of more
than three months was analysed.
The size and shape of the collared elephants home range was
calculated by using a Geographical Information System (GIS)
software that applies two methods, namely Minimum Convex
Polygon (MCP) method and Harmonic Mean (HM) method.
MCP involves drawing the smallest polygon using GIS that
contains all the location points for the tracked elephants. It is
considered that MCP is not suitable to be used for calculating
elephant home ranges. Osborne [31] highlights that MCP is
heavily influenced by outliers and the range increases as more fixes
are added. The other limitation of this method is that it does not
show the area of most activity. HM method of analysis attempts to
define a harmonic mean centre of activity. Range boundary
defined using HM method can be represented by the isopleths
enclosing the smallest matrix values [32]. Hence, the centre of
activities could be highlighted by HM method and concentrations
of activity are identified as the core areas if they are at the
periphery of the range.
In this study, the HM method was used to determine the size of
the home range, including the core area. The core area for the
elephant was identified with 65% isopleths, while the centre of
activity was identified with 85% isopleths, and home ranging or
area of distribution was identified with 95% isopleths.
Forest type and altitude range covered by a herd were
determined. Table 6 provides a brief description of the forest in
each capture location, and Table 7 lists the forest types in each
study area.
Conclusion
This study provides provisional evidence that elephant herds in
Sabah occupy a minimum home range between 250 km2 to
400 km2 in the non-fragmented forest, while in fragmented forest
habitat, the annual home range for elephants is estimated to be
around 600 km2.
The results also show that home range and movement rate for
the elephants are influenced by the degree of habitat
fragmentation. Once the key forest habitat for elephants is cleared, and the
availability of the food plants and water sources altered, elephants
are forced to expand and shift their ranges in the search for
resources to meet their needs. Therefore, these findings could
serve as a guideline where any habitat that is less than 500 km2
may not be suitable as a long-term territory for the Bornean
elephant. Consequently any fragmented forest habitat (below
500 km2) should be connected to other continuous and large forest
to secure a suitable area for the elephants to thrive.
The preferred habitat parameters for elephants were identified
by this study to be non-fragmented dipterocarp forest, on flat land
or with gentle slopes and below 300 meters elevation. Therefore,
the lowland dipterocarp forests of Sabah are considered the most
important habitat for the elephants, requiring high conservation
protection.
As part of the recommendations to ensure the conservation of
this species, two key recommendations are highlighted below: (i) all
remaining lowland dipterocarp forests which support wild
elephants should be retained under natural forest management
and must not be converted to plantations; and (ii) forest
disturbance needs to be minimized wherever wild elephants occur.
In timber production forests, this can be achieved by limiting the
extent and frequency of logging operations in any given
management compartment.
We would like to thank Datuk Sam Mannan, the Director of Sabah
Forestry Department for supporting our research in the forest reserves.
Also thanks to Roza Sipangkui and Elis Tambing from the Sabah Wildlife
Department and Jabanus Miun, Engelbert Dausip, William Joseph, Edwin
Matulin, Middle Seen Kapis, John Japil and David James from the Borneo
Species Programme for their involvement in the elephant satellite tracking
project. Finally, we thank Milena Salgado Lynn for correcting the English
of the paper and two anonymous reviewers for their valuable comments on
previous versions.
Conceived and designed the experiments: RA AHA JP CW LN PMH BG.
Performed the experiments: RA. Analyzed the data: RA JP CW BG. Wrote
the paper: RA BG.
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